Anarchists complain that I don't understand anarchism. They're probably right. But whose fault is that? I've never heard a convincing description of anarchism that didn't employ vague generalities. When I try to drill down to the specifics, I face increasing hostility and contempt, and I'm dismissed as
(Communism is, in contrast, relatively simple to describe: The "government" "owns" the capital; the people own the government. The devil is, of course, in the details, but communism is fundamentally predicated on the idea that concentrated capital is under present-day material circumstances orders of magnitude more effective than distributed capital, and there are mutually beneficial uses of capital that are not in any individual's or "freely associating" group's interest. Communism is not intended to be perfect or optimal, merely substantively less sub-optimal than modern capitalism.)
What precisely do anarchists mean by "authority" and "voluntary cooperation"? It's obviously not the case that anarchists are opposed to "authority" in the sense of expertise; it seems ridiculous to suppose that anarchists would consider it objectionable to label Bjarne Stroustrup as an authority on C++. Nor is it reasonable to suppose that anarchists oppose "definitional" authority: I can't see any sensible opposition to the idea that the distance traveled by light in free space in 1⁄299,792,458 of a second is the authoritative definition of the meter. It also doesn't seem sensible (to the extent that the Catholic church is to some extent a "voluntary association") to oppose the Pope's authority to define Catholic doctrine.
It seems logical at first glance to interpret the kind of authority that anarchists oppose as having something to do with coercion, the ability to force people to do things. Of course, coercion is (in an abstract sense) an ineluctable property of the physical universe; it would be ludicrous to be opposed to physics and entirely uncharitable to attribute that opposition to anarchists.
One might see anarchism as opposition to the "imposition" of coercive authority. This view, however, seems contradicted by the fact that there's no place to impose coercive authority from. All structures in human society — authoritarian or otherwise — are self-organized; they come from "within" the society.
(The anarchist opposition to "hierarchy" does seems really nonsensical; a small group that exercised coercive power should be objectionable even if it were organized other than hierarchically. For example, the capitalist ruling class employs hierarchical structures, but is not itself organized hierarchically. Similarly the self-organization of natural (non-human) ecosystems shows degrees of hierarchical organization, such as the "food chain" — strictly speaking a food web, but we can identify more-or-less hierarchical levels.)
Just by excluding plausible alternatives, we're almost forced to see anarchism as opposed in principle to any concentration of coercive power. (It must be "in principle" and "any"; were it otherwise, it would be something-archism, not nothing-archism.)
For coercion to not be concentrated, it must therefore be nearly perfectly distributed (any substantial deviation from perfect distribution is by definition concentration). But if coercion is perfectly distributed, then a majority of people can therefore arbitrarily* exercise coercive force on a minority. This "distribution" leads to Orwell's observation that,
In a Society in which there is no law, and in theory no compulsion, the only arbiter of behavior is public opinion. But public opinion, because of the tremendous urge to conformity in gregarious animals, is less tolerant than any system of law. When human beings are governed by 'thou shalt not', the individual can practise a certain amount of eccentricity: when they are supposedly governed by 'love' or 'reason', he is under continuous pressure to make him behave and think in exactly the same way as everyone else.It is simple observation that the rights and freedoms of minorities, including the individual as a minority of one, can be guarded only by a minority.
*Technically a redundancy; coercive force is necessarily exercised arbitrarily.
The only alternatives to unchecked democracy would be if it an individual or group was not able to coerce any individual, or if people were so constituted that they categorically did not want to coerce others. The former seems physically (and perhaps logically) impossible; the latter definitely not presently the case.
Another important consideration is that there are intrinsic variations in individuals and in the organization of more-or-less "voluntary" associations. These variations can combine naturally to afford some groups more power to effect their desires than other groups. And, of course, one natural desire is for more power. Not only does power naturally concentrate, but the concentration of power forms a positive feedback loop. In order to keep power distributed, some group would have to have the authority — the coercive power — to block or reverse natural concentrations of power. Concentration of power is necessary to stop concentration of power, a nifty paradox.
We have a similar situation regarding people's desires and will. It sure would be nice if people didn't want to coerce others, but people's desires tend to vary randomly. In order to have a population without some set of desires, someone has to actually select against those desires, i.e. to exercise coercive force. We don't actually solve the problem by operating on desires instead of actions, we just move the problem of "authority" to who gets to perform the selection of desires.
I think anarchism is not a coherent or realistic political philosophy, but I'm not at all against anarchism and anarchists. I think it's a Good Thing to have a group of people in the world implacably opposed to any concentration of coercive force. While it seems physically necessary under present-day and foreseeable circumstances to have some concentration of coercive force, i.e. some kind of authority, no authority should ever sleep easy, and anarchists are necessary to disturb their sleep.